‘The
eye and brain are not like a fax machine,
nor are there little people looking at the
images coming in’
– Torsten Wiesel

The
puzzle of seeingby
G. Sarcone

Our
brain is an artist that paints the reality that surrounds
us. It transforms energy into color;
links distances, movement and form to create reality in 3D;
interprets visual stimuli and compares them to memories...
and sometimes, it makes mistakes!

Are
the eyes an open door to the world, as poets say? Well, honestly,
not really. The fact is, we see the world through a pair of
tiny peepholes, the pupils of our eyes. Our brain functions
as a highly creative ‘camera
obscura’. The brain elaborates the visual stimuli
we receive, transforming them into true artworks.
The German poet Novalis said that the eye is a ‘superficial’ organ.
That is indeed partly true. I will even add that it is an external organ: the
eye with which we see the world is a part of the world itself. As soon as we
open the eye, whup, the world pops in it!
The eye is a humble and silent organ. It cannot ‘see’ itself,
and is itself unnoticed in use. Moreover, unlike a camera, the eye ‘creates’ a
field of vision without real edges. That seems paradoxical at first glance, that
our field of vision is limited but does not have boundaries... There are no ‘blank’ zones
outside of our visual field. Our brain simply cancels out those edges with a
smooth fade-out effect.

The
way we see and the way animals see

Light
from a scene passes through the pupil and strikes the eye's
retina where it is reproduced upside-down.

Here
is how our brain visually 'translate' the perceptive stimuli
from the eye.

Some
animals see differently than we do. Cats are red/green
color blind, and only perceive the blues and yellows
of the landscape.

Bulls have few retinal cones, and as a result, they have
no color vision. Also, their vision is much less
acute than ours.

Bees
and butterflies can see colors that we can't see. Their range
of color vision extends into the ultraviolet.

In
English, there are two essential families of words that we
use to express the faculty and the act of seeing: 1) ‘sight’, ‘see’,
and 2) ‘vision’, ‘view’. Looking at
these words etymologically, it seems most probable that they
originally came from words that meant, respectively, “to
follow something with the eyes” (from the Indo-European
*seqw-) and “to have learned” (from the
Indo-European *weid-). This suggests that, for our
ancestors, an image was something to shape with the eyes (follow
with the eye), a form of information taken from the real world
(learning through visual perception).
Unfortunately (or fortunately?), seeing isn’t some kind of
direct perception of reality. Atcually, our bairns are cnostanlty itnerperting,
corrceting and gviing srtuctrues to the viusal ipnut form our eeys (see footnote further
below). If this were not the case, we wouldn’t see any colors,
and we would probably see the world upside down! We would also notice in our
visual field a very large dot, called the blind spot, where the optical
nerve enters the eye.
Moreover, vision isn’t an innate process at all. It depends
to a large extent on ability acquired through a long and laborious undertaking.
We take the concept of vision for granted, but a person who is blind from birth
who later in life gains the sense of sight takes many years to learn how to understand
and organize the things that he now perceives. The
ability to see is a process far from banal, and far from being
passive. When we look at a panorama, its colors take around 30
milliseconds to arrive at the ‘visual cortex’ within
the posterior lobes of our brain (also known as ‘striate
cortex’ or ‘V1’). The shapes of the scene,
and the sensation of the distances – which involve depth
and motion – are perceived shortly after, at approximately
70 milliseconds. During these tiny slices of time, the brain
filters, analyzes, and interprets the various pieces of the visual
puzzle, trying to assemble them into a coherent image. In other
words, it is crafting the best and most useful scene possible
from the raw image data that our eyes present to us.

Visual
impairments tend to increase with age. As vision tends to blur,
contact lenses or glasses help improve eyesight. But sometimes
visual deficiencies pass unnoticed, or are even not preventable
or correctable, like colorblindness.

I’ve
always been fascinated and impressed by how people with partial
or total visual sensory deficiencies interact with the world.
We cannot talk about visual perception or optical illusions
without mentioning the other side of the coin... To understand
how these people ‘see’ without sight is to understand
just how important our sense of sight is (sometimes we don’t
do it justice or give it the importance it deserves) and how
it collaborates and integrates with the other sense organs.
Have you ever asked yourself what it is, when we see, walk, speak,
feel and touch all at the same time, that links our sight with the sense of touch
or hearing? The reality is we actually see very little: only that on
which we are concentrating, or which we find important. Man without
the crutches of the other sense organs would truly be lost, because it is they
which permit us, subconsciously, to go about our everyday lives. An experiment
demonstrated how at times we are really ‘blind’ in the truest sense
of the word. In this famous experiment on ‘inattentional blindness’,
performed in 1999, Daniel Simons and Christopher Chabris asked people to watch
a video clip and count the number of times one of two teams of basketball players
took possession of the ball. Many people (around 40 percent) didn’t notice
at all a man in a gorilla suit entering stage right, doing a jig in the centre
of the screen and then leaving, stage left. The clip demonstrated how we don’t
see what we don’t pay attention to, even when it’s in front of our
eyes!